Human Behavior Chapter 5: Sensation and Perception Part 2: Hearing, - PowerPoint PPT Presentation

Human Behavior Chapter 5: Sensation and Perception Part 2: Hearing, Taste, Smell, Touch

Hearing Parts of the Human Ear

How Hearing Works

Sound Waves …are Stimuli for hearing, they resemble waves or ripples of different sizes… Think of ripples on a pond…they travel through space at varying Heights and Speeds. The Height or the distance from the bottom to the top of a sound wave is called Amplitude.

Sound Waves Again, think of ripples on a pond…they travel through space at varying Heights and Speeds. The Speed or number of sound waves that occur within 1 second is called Frequency.

Amplitude (or Intensity): is the LOUDNESS of a sound, measured in decibels …0 ‐ 140+

Amplitude (or Intensity): is the LOUDNESS of a sound, measured in decibels …0 ‐ 140+

Decibel Scale

• Frequency is the PITCH of a sound and is measured in Hertz or Cycles

Frequency and Pitch A keyboard played at its highest key produces sound waves with a fast Frequency (4,000 Cycles/Hz per second) which results in a high pitch. A keyboard played at its lowest key produces sound waves with a slower Frequency (27 Cycles/Hz per second) which results in a low pitch.

Hearing Range Humans hear sounds only within a certain range of Frequencies (which decrease with age). Infants have the widest range from 20 ‐ 20,000 Cycles/Hz per second College Students on average range from 30 ‐ 18,000 Cycles/Hz per second A 70 Year Old may have trouble hearing sounds above 6,000 Cycles/Hz per second

Frequency Range

Hearing Range of Various Animals

Taste Your tongue has up to 10,000 taste buds…small bumps called papillae. Think of the papillae as a small hill on your tongue…in between those hills are trenches and on/in those trenches are taste buds. Each taste bud has anywhere from 5 ‐ 150 taste cells on it…they regenerate about once every two weeks.

• Insects have the most highly developed sense of taste. They have taste organs on their feet, antennae, and mouthparts. • Your entire tongue can taste all flavors; though some areas are more sensitive than others • Fish can taste with their fins and tail as well as their mouth. • In general, girls have more taste buds than boys. • Taste is the weakest of the five senses.

There are numerous tastes, but roughly 4 ‐ 5 primary tastes. Bitterness is the most sensitive taste for a reason…since a large number of natural bitter compounds are known to be toxic. The ability to detect bitter ‐ tasting, toxic compounds at low thresholds are considered to provide an important protective function.

Umami is an appetitive (the desire to eat) food taste and is described as a savory or meaty taste. It can be tasted in beef, cheese and soy sauce, and also found in many other fermented and aged foods, this taste is also present in tomatoes, grains, and beans.

Smell Olfaction/Olfactory system: Our noses house the systems that enable us to smell roughly 10,000 various scents…our Brains are what actually allows us to smell as the chemical stimuli in the air eventually have to be interpreted by the brain.

The Olfactory System

The Olfactory System At the top of the nasal cavity is the olfactory epithelium which is a layer of cells that contain the olfactory receptor cells/fibers. These fibers process the smell and move the chemical information to the olfactory bulb and from there to the centers of the brain for identification. If mucus in your nasal passages becomes too thick, air and odor molecules can’t reach your olfactory receptor cells. Thus, your brain receives no signal identifying the odor, and everything you eat tastes much the same .

Smell and Taste The sensation of flavor is actually a combination of taste and smell. That's because as you chew, you're forcing air through your nasal passages, carrying the smell of the food along with it; the odor molecules from food give us most of our taste sensation. Without that interplay of taste and smell, you wouldn't be able to grasp complex flavors, instead you'd be limited to the basic taste sensations picked up chemically by the tongue: salty, sour, sweet, bitter and umami Seventy to seventy ‐ five percent of what we perceive as taste actually comes from our sense of smell. If you hold your nose and start chewing a jelly bean taste is limited, but open your nose midway through chewing and then you suddenly recognize the flavor.

Taste and Smell Jellybean experiment: Taste two of the same flavored jellybeans. First round without smell (in order) writing down what flavor you think it is (without looking) and write down. Second round taste with smell, (but still do not look) write down and compare rounds.